1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method for calculating three-dimensional position information of an object by processing images taken at different frame time points by use of a plurality of cameras.
2. Description of the Related Art
Various research and development actions are now made concerning a visual perception processing system of a moving robot that follows a person. When the moving robot moves so as to follow a moving object such as a person, its visual perception processing system first takes images of the moving object and measures its three-dimensional positions by processing the images. According to the result of the measurement, the robot calculates the control amount of its driving system for movement.
Conventionally, there are known a person detection technology by background differences used in a monitoring system, and a technology for recognizing the head of a person by image processing, and these technologies may be applied to a visual perception processing system of a moving robot. However, because background images change greatly as the robot moves, the background difference method is not suitable for the visual perception processing system of the moving robot. Further, owing to positional relation with a person or a blockage etc., the head of an object to follow is not always taken in the visual range of the robot, and therefore, the person head recognition technology is also not effective. When it is taken into consideration that the moving robot makes its actions in the living space of the person, it is required for the robot to reduce data of a processing object and perform a high speed process.
Herein, there is known a technology for processing images taken at different frame time points (shutter timing) by use of a plurality of cameras, thereby calculating three-dimensional position information of an object at a high speed (for example, “High Speed three-dimensional Position Estimation using Differences in Shutter Timing between Cameras”, Shoichi Shimizu, Hironori Fujiyoshi, Proc. of MIRU2004, vol. 1, pp. 428-433, July, 2004).
In mounting the visual perception processing system to the moving robot, it is necessary to suppress a burden to a computer processing capacity provided in the robot as low as possible. The moving robot consumes its computer resources for not only its visual process but also moving mechanism control and other processes. Although processor performances are progressing, enhancing the computer processing capacity to a great extent leads to increased product costs. From these circumstances, there is a case where, in the visual perception processing system, a configuration is employed where image signals are taken in alternately from a plurality of cameras.
When a stereo image process is performed simply with a pair of images taken at different frame time points by use of plural cameras in order to calculate three-dimensional position information of an object, errors arising from differences of the frame time points occur, which has been a problem in the prior art.